Cartridge for an electrode array insertion device

ABSTRACT

A device, system and method for inserting a pre-curved electrode array ( 100 ) held in a substantially straight configuration by a straightening member ( 101 ) into a cochlea of a subject. As the electrode array ( 100 ) is inserted into the cochlea by the device, the straightening member ( 101 ) is held by the device such that the electrode array ( 100 ) advances off the straightening member ( 101 ) such that it is free to take on its pre-curved configuration in the cochlea of the subject.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a Continuation of U.S. patent application Ser. No.12/875,847, filed on Sep. 3, 2010, entitled “Cartridge for An ElectrodeArray Insertion Device”, now U.S. Pat. No. 8,909,349, which is aDivisional of U.S. patent application Ser. No. 10/505,075, entitled“Insertion Device for an Electrode Array,” filed on Mar. 10, 2006, nowU.S. Pat. No. 7,792,586 issued on Sep. 7, 2010, which is a nationalstage application of PCT Application No. PCT/AU2003/000229, filed onFeb. 24, 2003, which claims priority from Australian Provisional PatentApplication No. PS 0720, filed on Feb. 22, 2002, Australian ProvisionalPatent Application No. PS 0721, filed on Feb. 22, 2002, AustralianProvisional Patent Application No. PS 0722, filed on Feb. 22, 2002,Australian Provisional Patent Application No. PS 0723, filed on Feb. 22,2002, Australian Provisional Patent Application No. PS 0724, filed onFeb. 22, 2002, Australian Provisional Patent Application No. PS 1877,filed on Apr. 22, 2002, and Australian Provisional Patent ApplicationNo. 2002951152, filed on Sep. 2, 2002. Each of these documents is herebyincorporated by reference herein.

BACKGROUND

1. Field of the Invention

The present invention relates to a device, method and system for theinsertion of an electrode array into a cochlea of a subject and thesimultaneous removal of a straightening means of the electrode array.

2. Related Art

In many people who are profoundly deaf, the reason for deafness isabsence or destruction of, the hair cells in the cochlea which transduceacoustic signals into nerve impulses. These people are unable to derivesuitable benefit from conventional hearing aid systems, no matter howloud the acoustic stimulus is made, because there is damage to orabsence of the mechanism for nerve impulses to be generated from soundin the normal manner.

It is for this purpose that cochlear implant systems have beendeveloped. Such systems bypass the hair cells in the cochlea anddirectly deliver electrical stimulation to the auditory nerve fibers,thereby allowing the brain to perceive a hearing sensation resemblingthe natural hearing sensation normally delivered to the auditory nerve.U.S. Pat. No. 4,532,930 provides a description of one type oftraditional cochlear implant system.

Typically, cochlear implant systems have consisted of essentially twocomponents, an external component commonly referred to as a processorunit and an internal implanted component commonly referred to as astimulator/receiver unit. Traditionally, both of these components havecooperated together to provide the sound sensation to a user.

The external component has traditionally consisted of a microphone fordetecting sounds, such as speech and environmental sounds, a speechprocessor that converts the detected sounds, particularly speech, into acoded signal, a power source such as a battery, and an externaltransmitter coil.

The coded signal output by the speech processor is transmittedtranscutaneously to the implanted stimulator/receiver unit situatedwithin a recess of the temporal bone of the user. This transcutaneoustransmission occurs via the external transmitter coil which ispositioned to communicate with an implanted receiver coil provided withthe stimulator/receiver unit.

This communication serves two essential purposes, firstly totranscutaneously transmit the coded sound signal and secondly to providepower to the implanted stimulator/receiver unit. Conventionally, thislink has been in the form of a radio frequency (RF) link, but other suchlinks have been proposed and implemented with varying degrees ofsuccess.

The implanted stimulator/receiver unit traditionally includes a receivercoil that receives the coded signal and power from the externalprocessor component, and a stimulator that processes the coded signaland outputs a stimulation signal to an intracochlear electrode assemblywhich applies the electrical stimulation directly to the auditory nerveproducing a hearing sensation corresponding to the original detectedsound.

Traditionally, the external componentry has been carried on the body ofthe user, such as in a pocket of the users' clothing, a belt pouch or ina harness, while the microphone has been mounted on a clip behind theear or on the lapel of the user.

More recently, due in the main to improvements in technology, thephysical dimensions of the speech processor have been able to be reducedallowing for the external componentry to be housed in a small unitcapable of being worn behind the ear of the user. This unit allows themicrophone, power unit and the speech processor to be housed in a singleunit capable of being discretely worn behind the ear, with the externaltransmitter coil still positioned on the side of the user's head toallow for the transmission of the coded sound signal from the speechprocessor and power to the implanted stimulator unit.

Together with improvements in available technology, much research hasbeen undertaken in the area of understanding the way sound is naturallyprocessed by the human auditory system. With such an increasedunderstanding of how the .cochlea naturally processes sounds of varyingfrequency and magnitude, there is a need to provide an improved cochlearimplant system that delivers electrical stimulation to the auditorynerve in a way that takes into account the natural characteristics ofthe cochlea.

It is known in the art that the cochlea is tonotopically mapped. Inother words, the cochlea can be partitioned into regions, with eachregion being responsive to signals in a particular frequency range. Thisproperty of the cochlea is exploited by providing the electrode assemblywith an array of electrodes, each electrode being arranged andconstructed to deliver a cochlea stimulating signal within a preselectedfrequency range to the appropriate cochlea region. The electricalcurrents and electric fields from each electrode stimulate the nervesdisposed on the modiola of the cochlea.

It has been found that in order for these electrodes to be effective,the magnitude of the currents flowing from these electrodes and theintensity of the corresponding electric fields, are a function of thedistance between the electrodes and the modiola. If this distance isrelatively great, the threshold current magnitude must be larger than ifthe distance is relatively small. Moreover, the current from eachelectrode may flow in all directions, and the electrical fieldscorresponding to adjacent electrodes may overlap, thereby causingcross-electrode interference. In order to reduce the thresholdstimulation amplitude and to eliminate cross-electrode interference, itis advisable to keep the distance between the electrode array and themodiola as small as possible. This is best accomplished by providing theelectrode array in the shape which generally follows the shape of themodiola. Also, this way the delivery of the electrical stimulation tothe auditory nerve is most effective as the electrode contacts are asclose to the auditory nerves that are particularly responsive toselected pitches of sound waves.

In order to achieve this electrode array position close to the insidewall of the cochlea, the electrode needs to be designed in such a waythat it assumes this position upon or immediately following insertioninto the cochlea. This is a challenge as the array needs to be shapedsuch that it assumes a curved shape to conform with the natural shape ofthe inside wall of the cochlea and must also be shaped such that theinsertion process causes minimal trauma to the sensitive structures ofthe cochlea. In this sense, it is desirable that the electrode array isheld in a generally straight configuration at least during the initialstages of the insertion procedure.

Several procedures have been adopted to provide for an electrodeassembly that is relatively straightforward to insert while adopting acurved configuration following insertion in the cochlea. In this regard,it is known to make an electrode array that includes a spiral-shapedcarrier which has a natural spiral shape generally conforming to theconfiguration of a cochlea. Such an array may also include astraightening element or stylet to enable the carrier to be maintainedin a straight configuration for insertion. The straightening member isthen typically removed from the carrier following insertion therebyallowing the carrier to take on its natural spiral-shape and assume aposition adjacent the inner wall of the cochlea. Such a configuration isdescribed in the Applicant's issued U.S. Pat. No. 6,421,569.

Typically, the straightening member is removed following the insertionof the electrode array into the cochlea by clamping an exposed end ofthe straightening member with tweezers and gradually removing thestylet. This technique is difficult to coordinate and requires bothhands of a surgeon to perform.

One problem with such a technique is that it is difficult to control theinsertion process so that damage to the sensitive structures of thecochlea can be avoided. This is due to the fact that the cochlea has anatural spiral shape and the insertion of a substantially straightelectrode array into such a space will cause the array to impact uponthe walls of the cochlea, increasing the risk for damage to the cochleawalls if due care is not taken. It is typically not until the electrodearray is fully inserted that the transition of the array fromsubstantially straight to spirally curved is affected, hence the changetransition does not aid in the insertion process as such.

A number of tools have been developed to assist in the insertion of theelectrode array and subsequent removal of the straightening element.Typically, such devices have been difficult to use and have requiredcomplex sliding mechanisms to achieve the desired result. This hasresulted in tools that are difficult to manufacture, difficult to cleanfor re-use, have an increased probability of failure due to theircomplexity, and which have not been specifically designed to control theshape transition of the electrode array to aid in a non-traumaticinsertion procedure.

SUMMARY

In one aspect of the present invention, a cartridge configured to bereceived by an electrode array insertion device is disclosed. Thecartridge comprises an elongate body extending from a first end to asecond end and having a lumen extending therethrough, wherein theelongate body is configured to receive an electrode array in the lumen.The cartridge further comprises a window in a sidewall of the elongatebody configured to allow viewing of a portion of the electrode arraywhen the electrode array is positioned in the elongate body.

In another aspect of the present invention, a kit is disclosed. The kitcomprises a straightening member, a pre-curved electrode arrayconfigured to be maintained in a substantially straight configurationwhen the straightening member is positioned along a substantial lengthof the electrode array, and a cartridge. The cartridge comprises anelongate body extending from a first end to a second end and having alumen extending therethrough, wherein the elongate body is configured toreceive the electrode array in the lumen; and a window in a sidewall ofthe elongate body configured to allow viewing of a portion of theelectrode array when the electrode array is positioned in the elongatebody.

In yet another aspect of the present invention, a system for insertingan electrode array into a cochlea of a subject is disclosed. The systemcomprises a straightening member, a pre-curved electrode arrayconfigured to be maintained in a substantially straight configurationwhen the straightening member is positioned along a substantial lengthof the electrode array, a cartridge configured to receive the electrodearray; and an insertion device configured to receive at least a portionof the cartridge when the electrode array is positioned therein. Theinsertion device is configured to effect movement of the electrode arrayfrom a first position to a second position relative to the insertiondevice and to substantially prevent the straightening member from movingwith the electrode array from the electrode array's first position tothe electrode array's second position.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a fully assembled device according to apreferred embodiment of the present invention;

FIG. 2 is a schematic view of the partially assembled device of FIG. 1;

FIGS. 3a and 3b are schematic views of part of the electrode arraypositioning member of the device shown in FIG. 1;

FIG. 4 is a further schematic view of the partially assembled device ofFIG. 1;

FIG. 5 shows schematic views of part of the capture member of the deviceof FIG. 1;

FIGS. 6a-6f and 6j show part of a straightening member of an electrodearray;

FIGS. 6g, 6h, and 6i depict part of the straightening member beingcaptured by an embodiment of a capture member of the device of thepresent invention;

FIG. 7 is a view through a window of the device depicted in FIG. 1;

FIG. 8 is a further schematic part view of the device of FIG. 1;

FIGS. 9a, 9b and 9c show the device of FIG. 1 during the various stagesof insertion of an electrode array;

FIGS. 10a, 10b and 10c show a cartridge member according to anotheraspect of the invention; and

FIGS. 11a to 22c depict further embodiments of the device of the presentinvention.

DETAILED DESCRIPTION

A device of one embodiment of the present invention is generallydepicted as 10 in the accompanying drawings. The device 10 is used forinserting an electrode array 100 into a cochlea of a subject andremoving a straightening member 101 of the electrode array 100.

The device comprises a housing 11 which extends from a proximal end 12to a distal end 13. The distal end 13 is adapted to receive a portion ofthe electrode array 100.

The device further comprises an electrode array positioning member 14which extends through the housing 11 from a first end 15 to a second end16. The second end 16 engages part of the electrode array 100 such thatmovement of the electrode array positioning member 14 from a firstposition to a second position effects movement of the electrode array100 from a first position substantially within the housing 11 to asecond position substantially extending from the distal end 13 of thehousing 11.

The device 10 also has a capture member 17 which extends through thehousing 11 from one end 23 to a capture end 24. The capture end 24engages a portion of the straightening member 101 of the electrode array100 such that the straightening member 101 is restricted from movingwith the electrode array 100 from its first position substantiallywithin the housing 11 to its second position substantially extendingfrom the distal end 13 of the housing 11.

The electrode array positioning member 14 includes a plunger 18 at itsfirst end 15. When the device 10 is in use, a user exerts pressure onthe plunger 18 to cause movement of the electrode array positioningmember 14 from its first position to its second position, that is in adirection towards the distal end 13 of the housing 11. The plunger 18includes a thumb rest 19 which is adapted to abut with the proximal end12 of the housing 11. This abutment limits movement of the plunger 18towards the distal end 13 of the housing 11 thus ensuring that a userdoes not advance the electrode array 100 to an undesirable depth into acochlea of a subject.

A region 21 of the electrode array positioning member 14 adjacent to thesecond end 16 is slotted as depicted in FIG. 3a . The slotted region 21receives part of the straightening member 101 of the electrode array 100as described in further detail below. The slotted region 21 may alsoinclude a window as depicted in FIG. 3 b.

The slotted region 21 also receives a portion of the capture member 17.

The capture member 17 comprises an elongate member 22 which extends fromthe one end 23 to the capture end 24.

As shown in FIG. 5, the capture member 17 includes a flap member 25located adjacent the capture end 24. The flap member 25 is adapted toengage part of the straightening member 101 of the electrode array 100when said electrode array 100 is loaded onto the device 10.

As shown, the capture end 24 of the capture member 17 forms a hollowcylinder 26 which, when the device 10 is fully assembled, extends aroundthe second end 16 or a portion adjacent thereto of the electrode arraypositioning member 14 (as shown in FIGS. 2 and 4). The flap member 25extends from the capture end 24 and into the slotted region 21 of theelectrode array positioning member 14.

The straightening member 101 of the electrode array 100 extends througha central lumen or along a slot in the electrode array (not shown) andan engagement portion 103 extends beyond the proximal end 102 of theelectrode array 100. The straightening member 101 acts to straighten apre-curved electrode array thus enabling insertion of the electrodearray into the cochlea.

The engagement portion 103 of the straightening member 101 includes aball member 104, a loop 105, an arrow member 106, a bullet member 107 ora hemispherical member 108. As depicted in FIGS. 6a to 6d , theengagement portion includes loop 105 in combination with any one of ballmember 104, arrow member 106, bullet member 107 or hemispherical member108. In this regard, loop 105 is located further from the electrodearray 100 than either ball member 104, arrow member 106, bullet member107 or hemispherical member 108. A surgeon may therefore maintain theoption of inserting the electrode array 100 manually wherein the loop105 may be more easily captured by a hand tool such as a hook, forceps,tweezers or the like. Rather than grasping the loop 105, it is possibleto provide a surface 199 having a recess formed therein such that it mayform a concave face which may be captured either by the capture memberof the device or alternatively captured by a surgeon using a hand tool,such as a surgical pick.

In FIGS. 6e and 6f , the loop 105 is formed from an aperture 109 inbullet member 107. The aperture 109 enables a surgeon to capture thestraightening member 101 with a hand tool as mentioned above.

The electrode array 100 is loaded onto a cartridge member 29 withengagement portion 103 extending from one end of the cartridge member29. The end of the cartridge member 29 with the engagement portion 103extending therefrom is received within the distal end 13 of the housing11. As the cartridge member 29 is loaded onto said distal end 13, theengagement portion 103 moves through the slotted region 21 of electrodearray positioning member. 14. As discussed above, the flap member 25 ofthe capture member 17 extends into the slotted region 21.

If the flap member 25 is made from a resiliently flexible material, asthe engagement portion 103 moves into and along the slotted region 21 ofthe electrode array positioning member 14, the flap member 25 isdeformed by the engagement portion 103 as it passes said flap member 25.Once the engagement portion 103 has moved beyond the flap member 25, theflap member 25 resumes its original configuration, that is, extendingthrough the slot of the slotted region 21 of the electrode arraypositioning member 14.

The positioning of the flap member 25 extending through the slot of theslotted region 21 prevents any further movement of the engagementportion 103 in the reverse direction, that is, towards the second end 16of the electrode array positioning member 14.

FIGS. 6g to 6i show the engagement portion 103 passing the flap member25. In FIG. 6g , the engagement portion 103 includes ball member 104whereas in FIG. 6h , the engagement portion 103 includes a hemisphericalmember 108.

The engagement portion 103 shown in FIG. 6i includes an arrow member 106which has the advantage that it is has a gradual and longer taper thanthe ball 104 or the hemisphere 108.

With the electrode array 100 loaded onto the device 10, the second end16 of the electrode array positioning member 14 abuts with a proximalend 102 of the electrode array 100. The engagement portion 103 extendsinto the slotted region 21 of the positioning member 14 and is heldwithin the slotted region 21 by the flap member 25.

When the plunger 18 of the electrode array positioning member 14 ismoved in a direction towards the distal end 13 of the housing, thesecond end 16 of the electrode array positioning member 14 pushes theproximal end 102 of the electrode array 100 such that the electrodearray 100 is advanced from the distal end 13 of the housing 11, and whenused in a surgical procedure, advanced into a cochlea of a subject.

As the electrode array 100 is advanced into the cochlea, as detailedabove, the engagement portion—103 of the straightening member 101 isheld by the flap member. 25 of the capture member 17 and therefore thestraightening member 101 is restricted from advancing into the cochleawith the electrode array 100. There may be some advancement of thestraightening member 101 with the electrode array 100, however suchadvancement will only be relatively minimal until the flap member 25captures the engagement portion 103 of the of the straightening member101. Accordingly, the electrode array 100 advances off the straighteningmember 101 and into the cochlea. Substantially free of the straighteningmember 101, the electrode array 100 may then start to take on apre-curved configuration within the cochlea of the subject, allowing theelectrode array to assume a mid scala trajectory into the cochlea whichreduces the reliance on the sensitive structures of the walls of thecochlea to guide the electrode array into the cochlea. As a result, thisprovides a more efficient, safer, less traumatic, and potentially deeperelectrode array insertion procedure.

To fully remove the straightening member 101 from the electrode array100, the capture member 17 is moved in a direction towards the proximalend 12 of the housing 11. Such movement causes the flap member 25 of thecapture member 17 to abut with the engagement portion 103 of thestraightening member 101 and pull said engagement portion 103 along theslotted region 21 of the electrode array positioning member 14 in adirection towards the proximal end 12 of the housing 11.

The one end 23 of the capture member 17 is connected to a slide member31, which when the device is fully assembled, is located within thehousing 11. The slide member 31 includes two fingers rests 32 whichextend from the slide member 31 through two opposing slots 33 in thewall of the housing 11. A user moves the finger rests 32 along the slots33 to effect movement of the capture member 17. Movement of the fingerrests 32 in a direction towards the proximal end 12 of the housing 11will effect full withdrawal of the straightening member 101 from theelectrode array 100.

The device 10 further comprises a safety mechanism to prevent withdrawalof the straightening member 101 before the electrode array positioningmember 14 has moved to its second position and the electrode array 100advanced into the cochlea of a subject. In this regard, the slide member31 further includes a spring member 34 which is housed within a recessin the slide member. The spring member 34 is made from a resilientlyflexible material and includes “a main body 35 which on one side 36 ishingedly connected to a leg member 37. On an opposing side 38 of themain body 35, the spring member 34 includes a housing engagement portion39 which extends from the main body 35 and into a niche (not shown) inthe inner wall of the housing 11 of the device 10. When the housingengagement portion 39 is positioned within the niche of the housing 11,any movement of the spring member in either a direction towards thedistal end 13 or the proximal end 12 of the housing 11 is prevented. Asthe spring member 34 is housed within the slide member 31, the slidemember 31 and the capture member 17 (which is connected to said slidemember 31) are prevented from moving in either direction.

The slide member 31 and the main body 35 of the spring member 34 furtherinclude a groove 40 which receives a portion of the electrode arraypositioning member 14 and allows the electrode array positioning memberto pass therethrough.

The electrode array positioning member 14 comprises a number ofcomponents connected to or integral with one another. The plunger member18 comprises a thumb rest 19 connected to or integral with a pushing arm41. The pushing arm 41 is connected to or integral with an intermediatemember 42 which has a smaller cross-sectional diameter than the pushingarm 41. Finally, the intermediate member 42 is connected to or integralwith an end member 43.

The end of the pushing arm 41 which is connected to the intermediatemember 42 is slightly tapered in its join with the intermediate member42. Accordingly, said end of the pushing arm 41 which joins with theintermediate member 42 forms a shoulder 44.

In use, the intermediate member 42 passes through the groove 40 of theslide member 31 and the spring member 34 when the plunger 18 is actuatedand the electrode array 100 advanced into a cochlea. Movement of theintermediate member 42 through the groove 40 does not disrupt theconfiguration of the spring member 34. Accordingly, if the spring member34 is positioned such that the housing engagement member 39 is withinthe niche in the housing 11, movement of the intermediate member 42through the groove 40 does not dislodge the housing engagement member 39and thus the spring member 34, slide member 31 and capture member 17 arefixed in position relative to the housing 11. This enables the electrodearray positioning member 14 to be moved to its second position withoutthe straightening member 101 of the electrode array 100 being withdrawnprematurely from said array.

As the electrode array positioning member 14 reaches its secondposition, the tapered end of the pushing arm extends into the groove 40until the shoulder 44 of the pushing arm 41 pushes against a wall of thegroove 40 of the main body 34. This causes the main body 34 to moveabout its hinged joint with the leg member 37 from a first positionwherein the main body 34 is relatively spaced from the leg member 37 toa second position wherein said main body 34 is relatively less spacedfrom the leg member 37. Such movement of the main body 34 of the springmember 34 disengages the housing engagement member 39 from the niche inthe inner wall of the housing 11. With the housing engagement member 39disengaged from the inner wall of the housing 11, the slide member 31and the capture member 17 are free to be moved by way of the fingerrests 32 in a direction towards the proximal end 12 of the housing 11.

The housing 11 is tapered towards the distal end 13 to form a tip member50 suitable for introduction into a patient. The tip member 50 may beintegral with the remainder of the housing 11 or may in the alternativebe detachable from the remainder of the housing 11-11^-shown in FIG. 2.

Further, the tip member 50 is angled relative to the remainder of thehousing 11 to provide a good line of vision for a surgeon duringinsertion of the electrode array 100. The electrode array positioningmember 14 and the capture member 17 are also angled along their lengthto correspond with the angled structure of the housing 11.

The tip member 50 of the housing 11 includes a window 46 to allow a userto view the electrode array 100 once said array is loaded onto thedevice 10. If loaded correctly, the user should be able to view theengagement portion 103 of the straightening member 101 through thewindow as shown in FIG. 7.

FIGS. 9a, 9b and 9c show the device during the various stages of asurgical procedure. The plunger 18 is steadily moved towards theproximal end 12 of the housing 11 until it abuts with the proximal end12 and cannot be moved any further. As depicted, the movement of theplunger 18 advances the electrode array 100 from the distal end 13 ofthe housing 11. As the straightening member 101 is held by the capturemember 17 of the device 10, the electrode array 100 advances off thestraightening member and from the housing 11, whereupon it takes on apre-determined-curved configuration. The finger rests 32 may then bedrawn back towards the proximal end 12 of the housing 11 such that thestraightening member 101 is fully removed from the electrode array 100.

A cartridge member as defined in the third aspect of the invention isgenerally depicted as 129 in the accompanying drawings. The cartridgemember 129 is shown when used with electrode array 100 which hasstraightening member 101 extending therefrom.

As depicted in FIGS. 10a, 10b and 10c , the cartridge member 129includes an elongate body 130 which extends from a first end 131 to asecond end 132. The elongate body 130 has an internal lumen 133 whichextends therethrough and which is adapted to receive the electrode array100.

The cartridge member 129 further includes a slot 134 along a portion ofthe length of the elongate body to accommodate the electrical leads ofthe electrode array 100 and a window 135 in a portion of the sidewall ofthe elongate body 130 adjacent the first end 131. The window 135 enablesa user to view a portion of the electrode array 100 which is positionedwithin the lumen 133 of the cartridge member 129.

The electrode array 100 is loaded onto the cartridge member 129 byfeeding the engagement portion 103 of the straightening member 101 ofthe electrode array 100 into the second end 132 of the cartridge member.The electrode array 100 is oriented such that the electrical leads ofthe electrode array 100 are substantially aligned with the slot 134along the elongate body 130 of the cartridge member 129. The electrodearray 100 is then guided into the cartridge member 129 by pullinglightly on the electrical leads of the electrode array 100 until theball 104 and loop 105 extend from the first end 131 of the cartridgemember 129.

The cartridge member 129 and electrode array 100 may be used with device10 as depicted in FIGS. 10b and 10c . The cartridge member 129 is loadedonto the distal end 13 of the housing 11 and the electrode arraypositioning member 14 of the device 10 caused to engage the electrodearray 100 within the cartridge member 129.

As mentioned above, a portion of the housing 11 adjacent the distal end13 includes a window 46. As the cartridge member 129 is loaded onto thedevice 10, the window 135 of the cartridge member 129 is aligned withthe window 46 in the housing 11 of the device 10.

FIGS. 11a to 11d show a further embodiment of device 10 of the presentinvention wherein the electrode array positioning member 14 comprises anelongate member extending from first end 15 to second end 16. Second end16 is forked to maximize engagement with electrode array 100. In thisembodiment, the positioning member includes a plunger 18 at its firstend 15. Movement of the plunger 18 in the direction shown by the arrowin FIG. 11d causes the electrode array 100 to move from the distal endof the housing 11 and into a cochlea of a patient.

The capture member 17 of this embodiment comprises a tie member 150which is anchored at one end 151 to an anchor 152 located on a wall ofthe housing 11. At its second end 153 the tie member 150 engages theengagement portion 103 of straightening member 101. In this case, thetie member forms a loop at the second end 153 to engage a complementarypart of the engagement portion.

As the housing 11 of this embodiment remains relatively fixed in theforward direction during the insertion procedure, as the electrode arrayis advanced into the cochlea, the engagement portion 103 of thestraightening member is held by the tie member 150 and thus theelectrode array 100 advances off the straightening member 101.

This embodiment has a number of safety features including a cochleostomystopper 154 positioned adjacent the distal end 13 of the housing 11.During an insertion procedure, the cochleostomy stopper 154 abuts withan edge of a cochleostomy such that the housing 11 is prevented fromadvancing too far into a cochlea of a subject.

Other safety features include a means to prevent the electrode array 100from advancing too far into a cochlea of a subject thereby damaging thesurrounding tissue. In this regard, the electrode array positioningmember 14 includes a second stopper 155 located at a position along itslength. The second stopper 155 abuts with a portion of the housing 11such that the electrode array positioning member 14 is prevented frommoving any further in a direction towards the distal end 13 of thehousing 11.

A further embodiment of device 10 is depicted in FIGS. 12, 12 a, 12 b,13, 13 a and 13 b. The housing 11 comprises a handle 160 and a tipmember 161. The tip member 161 includes the electrode array positioningmember 14 which comprises an inner member 162 which is slidablyreceivable within an outer member 163. The inner member 162 comprises anelongate tubular structure extending from a first end 164 connected tothe handle 160 to a second end 165 adapted to receive electrode array100. The tubular structure of the inner member 162 defines an internallumen 159 extending therethrough.

The outer member 163 also comprises a tubular structure defining aninternal lumen 170. The outer member 163 extends from a proximal end 166relatively adjacent the handle 160 to a distal end 167 relatively distalthe handle 160. The outer member 163 further includes capture member 17positioned along the length of the outer member 163.

The handle 160 comprises a plunger member 168 which, when the device isin use, is moved forward relative to the outer member 163 and in adirection towards the cochlea (not depicted) of the subject. As theinner member 162 is connected to the handle 160, such movement causesthe inner member 162 to move longitudinally forward relative to theouter member 163 until at least part of the inner member extends beyondthe distal end 167 of the outer member 163. This action advances theelectrode array 100 forward of the outer member 163 and into thecochlea.

The outer member 163 includes a cochleostomy stopper 154 as depicted inFIGS. 12a and 13a . The cochleostomy stopper 154 is located adjacent thedistal end 167 of the outer member 163. In use, the cochleostomy stopper154 abuts with the edge of a cochleostomy (not shown) thereby preventingthe outer member 163 from moving into the cochlea. In this way, theouter member 163 is substantially fixed in a position and cannot movefurther into the cochlea during use of the device 10.

The capture member 17 comprises a flap member 25 as depicted in FIGS.12a, 12b, 13a and 13b . The flap member 25 extends from a wall 169 ofthe outer member into the lumen 170 of the tubular outer member 163 andthrough a slot 158 in the wall of the inner member 162 such that itextends into lumen 159 of the inner member 162.

In this embodiment, the engagement portion 103 of the straighteningmember 101 of the electrode array 100 is depicted as a loop 105 which isengaged by flap member 25.

To fully remove the straightening member 101 from the electrode array100, the device 10 may further include a tie line 171. The tie line 171is connected at a first end 172 to an actuator member 173 located onhandle 160. At a second end 174, the tie line 171 is connected to loop105 of straightening member 101.

The tie line 171 is a flexible cord made from a suture-type material.Such 5 material has the advantage that it is biocompatible.

The actuator member 173 is a sliding means 175 which is movable along alength of the handle 160.

As the sliding means 175 is pulled back away from the surgical site, thetie line 171 is pulled taut such that the straightening member 101together with the outer member 163 (as the outer member is in engagementwith the straightening member via the capture member) are pulled awayfrom a cochleostomy thereby fully withdrawing the straightening member101 from the electrode array 100.

In the embodiment of the invention depicted in FIGS. 13, 13 a and 13 b,the device 10 includes a pulling rod 176 which is connected at one end177 to the sliding means 175 and connected at a second end 178 to theproximal end 166 of the outer member 163. Movement of the sliding means175 in a direction away from a surgical site causes the outer member 163to withdraw from the cochleostomy site. As the capture member 17 of theouter member 163 is in engagement with engagement portion 103 ofstraightening member 101, movement of the sliding means 175 in thismanner fully withdraws the straightening member 101 from the electrodearray 100.

In the embodiment of the invention depicted in FIG. 14, the outer member163 comprises the electrode array positioning member 14 which isconnected to plunger member 168. The inner member 162 includes thecapture member 17 ie flap member 25 on a wall of the inner member andextending into lumen 159 of inner member 162.

Movement of plunger member 168 causes movement of the outer member 163relatively towards a surgical site such that the electrode array 100 isadvanced into a cochlea of a subject. The outer member 163 may bedirectly connected to the handle 160 as depicted in FIG. 14 or,alternatively connected to the handle by a piston member 180 as depictedin FIGS. 15, 15 a and 15 b.

The pulling rod 176 is connected at its second end 174 to the first end164 of the inner member 162. Movement of the sliding means 175 in adirection away from a surgical site causes the inner member to move awayfrom the surgical site thereby fully withdrawing the straighteningmember 101 from the electrode array 100.

The device shown in FIGS. 17 and 17 a, b and c has a housing 11 whichcomprises an inner member 162 and an outer member 163. The inner memberis received within lumen 170 of the outer member 163. The electrodearray positioning member 14 in this embodiment may be seen as anelongate pushing rod 190 which extends through lumen 159 of inner member162, along a substantially length of the inner member 162.

The inner member 162 includes the capture member which typicallycomprises flap member 25 extending from a wall of the inner member 162and into the lumen 159 of inner member 162. The capture member engagesengagement portion 103 of the straightening member which extends intothe lumen 159 at the second end 165 of the inner member 162 when anelectrode array is loaded onto the device.

The electrode array is advanced into the cochlea 300 during a procedureby pushing plunger 18. As the electrode array positioning memberadvances towards the cochlea 300 of a subject, the inner member 162 isheld in a relatively fixed manner such that it cannot move in saidforward direction. The electrode array 100 therefore advances off thestraightening member 101. Alternatively or in addition to, the electrodearray positioning member 14 may include an actuator member 191. Theactuator member 191 extends from the elongate pushing rod 190 andthrough slots in the walls of the both the inner member 162 and theouter member 163. The actuator member 191 may be moved along said slotsto actuate movement of the electrode array positioning member 14.

As depicted in FIGS. 18a and 18b , the second end 16 of the electrodearray positioning member 14 includes a recessed portion 192 toaccommodate engagement portion 103 of the straightening member 101. Inthis regard, the electrode array loaded on the device 10 may be moved bypushing the pushing rod against a proximal end 200 of the electrodearray rather than pushing against engagement portion 103. This preventsdamage to the engagement portion 103 which is housed in said recessedportion 192.

The embodiment of the invention depicted in FIGS. 19, 19 a and 19 b showhow the elongate pushing rod 192 may be moved by movement of theactuator member 191. Rather than being connected to or forming part ofthe elongate pushing rod 190, the actuator member is brought intoengagement with a proximal end 193 of the pushing rod 190.

The actuator member is a slide which may move along slots in the innerand the outer members. The actuator member 191 further includes anextension member 194. When the pushing rod 190 is in its secondposition, the extension member 194 abuts with a wedge 195 that inwardlyextends from a wall of the inner member 162 and into lumen 159 of innermember 162. The extension member 194 is relatively rigid in structureand when the actuator member 191 is withdrawn from the surgical site,the extension member 194 exerts pressure on the wedge member 195 therebycausing the inner member 162 to also move in a direction away from thesurgical site. As the inner member 162 includes the capture member 17,such movement allows full withdrawal of the straightening member 101 ofan electrode array 100.

In the embodiment of the invention depicted in FIGS. 20 and 20 a, thecapture member 17 includes a pair of jaw members 200 at its capture end24. The jaw members 200 are made from a suitably malleable material toallow movement of said jaw members 200 from a first open position (shownin FIG. 20) to a second closed position (shown in FIG. 20a ). The jawmembers 200 are moved to their closed position by movement of theelectrode array positioning member 14 which in this embodiment comprisesinner member 162. In this regard, the jaw members 200 may be held byelongate member 201 which extends through lumen 159 of inner member 162.The jaw members 200 extend from the second end 165 of the inner member162 and flare outwardly from said second end 165. Movement of the innermember 162 by actuator member 191 causes the second end 165 of the innermember 162 to abut with the flared out jaw members 200.

The continued force applied to the jaw members 200 as the inner member162 moves from its first to its second position causes said jaw members200 to deform and take on their second closed position thereby capturingthe engagement portion 103 of the straightening member of an electrodearray 100 loaded onto the device 10.

The capture member is prevented from moving in the direction of theinner member 162 by stopper member 204 which abuts with a shoulder 205of a recessed section 206 of the capture member 17.

The capture member 17 of this embodiment further includes a latch member202 which engages actuator member 191 when the inner member 162 is inits second position. By moving the actuator member 191 in a reversedirection, away from a surgical site, said actuator member abuts with ashoulder 203 of the latch member 202 such that the latch member 202 andthe capture member 17 are caused to move in said direction away from thesurgical site such that the straightening member 101 is fully removedfrom the electrode array 100.

The device 10 includes a safety clip 210 which is depicted in FIG. 21,and when used with the device 10 in FIG. 22a, b and c . The safety clip210 prevents premature movement of the electrode array positioningmember 14 and thus movement of the electrode array 100.

The safety clip 210 is clipped onto a region of the electrode arraypositioning member 14 adjacent its first end 15. In the embodimentdepicted, a region of the electrode array positioning member 14 adjacentsaid first end 15 extends beyond the proximal end 12 of the housing 11.Movement of the first end 15 of the electrode array positioning membertowards the proximal end 12 of the housing allows the electrode array100 to advance off straightening member 101 and into a cochlea of asubject. The safety clip 210 abuts with the proximal end 12 of thehousing 11 thereby preventing any such forward movement of the electrodearray positioning member 14.

Further Embodiments

In a first aspect, the present invention consists in a device forimplanting an electrode array into the body of a subject and removing astraightening member of the electrode array, the device including a mainbody which extends from a proximal end to a distal end wherein thedistal end receives at least a portion of the electrode array, thedevice further including an electrode array positioning member that ismovable from a first position to a second position, said movement of theelectrode array positioning member from its first position to its secondposition effecting movement of the electrode array from a first positionwherein it is housed relatively within the main body to a secondposition wherein a substantial length of the electrode array extendsfrom the distal end of the main body; the device further including acapture member which engages at least a portion of the straighteningmember of the electrode array and restricts said straightening membermoving with the electrode array to its second position upon movement ofthe electrode array positioning member.

In a preferred embodiment, the electrode array is implanted in a cochleaof a subject.

In a second aspect, the present invention provides a system forinserting an electrode array into a cochlea of a subject, said systemcomprising:

a pre-curved electrode array maintained in a substantially straightconfiguration by a straightening member positioned along a substantiallength of said array; and

an insertion device for receiving said electrode array;

wherein the electrode array is advanced into the cochlea of a subject bythe insertion device and further wherein the straightening member of theelectrode array is substantially prevented from advancing into thecochlea by said insertion device such that as the electrode array isadvanced into the cochlea said electrode array can gradually assume itspre-curved configuration thereby adopting an advancement path thatconforms with the natural shape of the cochlea.

In a third aspect, the present invention provides a system for insertingan electrode array into a cochlea of a subject, said system comprising;

a pre-curved electrode array maintained in a substantially straightconfiguration by a straightening member positioned along a substantiallength of said array;

a loading cartridge for receiving said electrode array; and

an insertion device for receiving said loading cartridge with saidelectrode array positioned thereon;

wherein the insertion device causes the electrode array to advance fromthe loading cartridge and into the cochlea of a subject whilstsubstantially preventing the straightening member of the electrode arrayfrom advancing into the cochlea such that as the electrode array isadvanced into the cochlea said electrode array can gradually assume itspre-curved configuration thereby adopting an advancement path thatconforms with the natural shape of the cochlea.

Preferably, the main body of the device forms a housing extending fromthe proximal end to the distal end. The housing may include a handle anda tip member

wherein the handle and tip member may be integral with one another oralternatively, the tip may be removably connected to the handle. Thehousing may also include an inner member positioned at least partiallywithin an outer member.

The electrode array positioning member may comprise a number ofstructures and may be moved from its first position to its secondposition by a number of means. In each embodiment discussed below, itmay be seen that movement of the electrode array positioning member in adirection towards the distal end of the housing relative to asubstantially fixed capture member allows the electrode array which hasbeen loaded onto the device to effectively “advance off” thestraightening member.

In a preferred embodiment, said electrode array positioning membercomprises an elongate member that substantially extends through saidhousing from a first end to a second end, said second end adapted toengage part of the electrode array.

With reference to movement of the electrode array positioning member,the electrode array positioning member may be connected to the handle ofthe housing such that as the handle is moved in a direction towards thedistal end of the housing, said electrode array positioning member isalso moved in said direction. In use, this embodiment enables a surgeonto manipulate the device of the present invention much like a pen.

Alternatively, the electrode array positioning member may comprise aplunger member. In this embodiment, it is preferred that a length of theelectrode array positioning member adjacent the first end of theelectrode array positioning member extends beyond the proximal end ofthe housing. When the device is in use, the surgeon may exert pressureon the plunger member to cause movement from its first position to itssecond position. The plunger member typically includes an actuatormember at its first end wherein said actuator member, which may be athumb rest, is adapted to abut with the proximal end of the housing.This abutment limits movement of the electrode array positioning membertowards the distal end of the housing thus ensuring that a user does notadvance an electrode array too far into a cochlea of a subject.

Still further, the electrode array positioning member may be connectedto or brought into engagement with a slider such that movement of theslider towards the distal end of the housing causes movement of saidelectrode array positioning member in said direction. The slider maymove along a slot in the wall of the housing and include finger rests toenable a user to move the slider along said slot.

The second end of the electrode array positioning member may be forked,grooved or slotted to optimize engagement with the electrode array.

Alternatively, at least a portion of the electrode array positioningmember adjacent the second end may comprise a substantially hollowcylinder defining an internal lumen therein. In this regard, it ispreferred that in addition to being adapted to engage and position anelectrode array, the lumen of the electrode array positioning memberalso receives an engagement portion of the straightening member of theelectrode array.

Similarly, the electrode array positioning member may include a groovedor recessed portion at or adjacent its second end to receive theengagement portion of the straightening member.

In another embodiment, the housing may include an inner member and anouter member. The inner member and the outer member typically make uppart of the tip member of the housing and are configured such that oneof said inner member or outer member is fixed relative to the othermember such that the relatively “movable” member may include theelectrode array positioning member and the substantially “fixed” membermay include the capture member.

The capture member may include a number of structures but in eachembodiment has the feature that it engages and “captures” the engagementportion of the straightening member such that as the electrode array isadvanced into a cochlea of a subject during a procedure, the engagementportion of the straightening member is held by the capture member andthe electrode array is allowed to “advance off” the straighteningmember. In this regard, the capture member may be essentially fixedrelative to the electrode array positioning member.

By the term “substantially fixed”, it is considered that the capturemember does not substantially move in a direction towards the distal endof the housing of the device, which, when the device is in use, istowards a cochlea of a subject. It is envisaged, however, that thecapture member may be moved relatively in a direction away from thedistal end of the housing such that the straightening member of theelectrode array may be fully removed from an electrode array.

In a preferred embodiment, the capture member may comprise an elongatemember which extends from one end to a capture end. At or adjacent thecapture end said capture member may include a flap, hook, loop or tie orany member capable of engaging with the engagement portion of thestraightening member when said electrode array is loaded onto the deviceof the present invention.

Alternatively, the capture end may include a pair of jaw members whichare movable from a first open position to a second closed position suchthat in the second closed position, the jaw members clamp around theengagement portion of the straightening member.

Rather than an elongate member extending through the main body, thecapture member may include a member positioned on or forming part of awall of the housing. For instance, in the embodiment having a tip memberwhich comprises an inner member and an outer member, the capture membermay be positioned on one of said inner or outer members. As discussedabove, one of the inner member or the outer member is movable relativeto the other that is substantially fixed. The capture member may bepositioned on said substantially fixed member. The capture member mayinclude a flap, hook, loop or tie or any member capable of engaging withthe engagement portion of the straightening member.

It is also preferred that at least a portion of the electrode arraypositioning member adjacent its second end includes a slot along itswall. Said slotted portion may receive at least part of the capturemember.

In the embodiment wherein the electrode array positioning member is anelongate structure extending from a first end to a second end and thecapture member also comprises an elongate structure extending from oneend to a capture end, it is envisaged that the capture end of thecapture member may comprise a substantially hollow cylinder. The secondend or a portion adjacent the second end of the electrode arraypositioning member is receivable within a lumen formed by thesubstantially hollow cylinder of the capture member. The flap, hook,loop or tie member of the capture member preferably extends inwardly ofthe capture end such that it may engage the engagement portion of thestraightening member received by the electrode array positioning member.

In the embodiment wherein the capture member is positioned on a wall ofan inner member or an outer member of the tip member of the housing, itis preferred that the inner member and the outer member aresubstantially hollow in structure such that the inner member is slidablyreceivable within the outer member.

In one embodiment, the electrode array positioning member may comprisethe inner member. In this embodiment, the capture member is positionedon the outer member such that at least part of the capture memberextends through the slotted portion of the electrode array positioningmember.

In another embodiment, the electrode array positioning member maycomprise the outer member and the inner member includes the capturemember. In this embodiment, the electrode array may be received withinboth the inner and the outer members such that the engagement portion ofthe straightening member of the electrode array extends into the lumenof the inner member and engages with the capture member. The outermember engages the electrode array such that as the outer member ismoved so too is the electrode array.

The capture member preferably includes a flap member made from aresiliently flexible material such as a plastics material. In thisembodiment, the principle of capture of the engagement portion of thestraightening member of the electrode array relies upon movement ordeformation of the flap member caused by movement of the engagementportion through the lumen of the electrode array positioning member asthe electrode array is loaded onto the device of the invention. In thisregard, the force of the moving engagement portion of the straighteningmember against the flap member causes the flap member to move from afirst position substantially occluding the lumen of the electrode arraypositioning member to a second position which allows passage of theengagement portion of the straightening member past the flap member.Upon release of the “deforming” force, i.e. once the engagement portionhas passed the flap member, said flap member may return to its originalconfiguration such that it substantially occludes the lumen of theelectrode array positioning member and prevents the engagement portionfrom moving in a reverse direction. This may be achieved in a number ofways as discussed in further detail below.

Alternatively, the capture member may include a hook, press stud, orother like member that extends from the capture member and into thelumen of the electrode array positioning member whereupon it engages acomplementary structure such as a loop member comprising the engagementportion of the straightening member.

In the embodiment wherein the capture member includes a pair of jawmembers at its capture end, it is envisaged that the jaw members aremade from a suitably malleable material to allow movement of said jawmembers from a first open position to a second closed position. In oneembodiment, the jaw members may be moved to their closed position bymovement of the electrode array positioning member. In this regard, thecapture member may be positioned within at least the substantiallyhollow cylinder of the second end of the electrode array positioningmember such that the jaw members extend beyond the second end and flareoutwardly from said second end. Movement of the electrode arraypositioning member to its second position causes the second end of theelectrode array positioning member to abut with the flared out jawmembers. The continued force applied to the jaw members as the electrodearray positioning member moves from its first to its second positioncauses said jaw members to deform and take on their second closedposition thereby capturing the engagement portion of the straighteningmember of an electrode array loaded onto the device.

The straightening member of the electrode array typically extendsthrough a central lumen or along a slot in the electrode array from aproximal end of said electrode array to a leading tip of the electrodearray. The straightening member acts to straighten a pre-curvedelectrode array thus enabling insertion of the electrode array through acochleostomy and into the cochlea.

Typically, said engagement portion of the straightening member which iscaptured by the capture member extends beyond the proximal end of theelectrode array and may include a number of structures including but notlimited to a substantially spherical member, a hemispherical member, aconical member, a bullet-like member, or an arrow-shaped member.Alternatively, as mentioned above, the engagement portion may include aloop or other like structure or a combination of a loop with any one ofthe substantially spherical, hemispherical, conical, bullet-like, orarrow-shaped members. In this latter embodiment, it is preferred thatthe loop is located furthest from the electrode array than either thesubstantially spherical, hemispherical, conical, bulletlike, orarrow-shaped member. This has the advantage that a surgeon may maintainthe option of inserting the electrode array manually wherein the loopmay be more easily captured by a hand tool such as a hook, forceps,tweezers or the like.

In a further embodiment, the engagement portion of the straighteningmember may comprise a structure such as a substantially spherical,hemispherical, conical, bullet-like, or arrow-shaped member having anaperture therein such that said aperture may act as a means of manualcapture of the straightening member and the substantially spherical,hemispherical, conical, bullet-like, or arrow-shaped member as a meansof deforming the flap member and resulting in capture of the engagementportion of the straightening member.

In one embodiment, the electrode array may be loaded into a cartridgemember with the engagement portion of the straightening member extendingfrom one end of the cartridge member. The end of the cartridge memberwith the engagement portion of the straightening member extendingtherefrom is received within the distal end of the housing of thedevice. As the cartridge member is loaded onto said distal end, saidportion of the straightening device may be caused to move through thelumen of the substantially hollow portion of the electrode arraypositioning member and along the slotted portion of the electrode arraypositioning member.

As discussed above, at least part of the capture member may extend intothe slot formed in the wall of said slotted portion. Where the capturemember includes a flap member, the flap member typically extends intoand substantially occludes the lumen of the hollow cylinder of theelectrode array positioning member. In the embodiment wherein the flapmember is made from a resiliently flexible material, as the engagementportion of the straightening member is moved into and along the slottedportion of the electrode array positioning member, the engagementportion of the straightening member is forced against the flap membercausing said flap member to move or deform such that it no longersubstantially occludes the lumen of the electrode array positioningmember. This allows the engagement portion of the straightening memberto pass the flap member. Once the engagement portion of thestraightening member has moved beyond the flap member, the flap membermay resume its original configuration extending through the slot of theslotted portion of the electrode array positioning member and into thelumen of the electrode array positioning member and substantiallyoccluding said lumen.

Typically, the flap member may only be movable or deformable in onedirection to allow the engagement portion of the straightening member topass. The flap member therefore acts as a “one-way gate” for theengagement portion of the straightening member.

In a preferred embodiment, when the electrode array is loaded onto thedevice, the second end of the electrode array positioning member abutswith the proximal end of the electrode array. In the embodiment whereinthe electrode array positioning member comprises a plunger member, whenthe plunger member is moved in a direction towards the distal end of thehousing, the second end of the electrode array positioning member pushesthe proximal end of the electrode array such that the electrode array isadvanced from the distal end of the housing, and when used in a surgicalprocedure, advanced into a cochlea. of a subject.

As the electrode array is advanced into the cochlea, the engagementportion of the straightening member captured by the flap member is heldby the “one way gate” system of the flap member and thus prevented fromadvancing with the electrode array. The entire straightening member is,therefore, prevented from advancing into the cochlea with the electrodearray and the electrode array “advances off” the straightening memberand into the cochlea. Substantially free of the straightening member,the electrode array may then start to take on a pre-curved configurationwithin the cochlea of the subject.

To fully remove the straightening member from the electrode array, thecapture member may be moved in a direction towards the proximal end ofthe housing. Where the capture member includes a flap member, suchmovement causes the flap member to abut with part of the engagementportion of the straightening member and pull the engagement portion ofthe straightening” member along the slotted portion of the electrodearray positioning member in a direction towards the proximal end of thehousing.

In this regard, the capture member may be connected to a slide memberwhich may be positioned on an outer wall of the housing or,alternatively, within the housing and having a portion extending fromthe housing to enable manipulation of said slide member by a user. Thecapture member may be connected to said slide member by a number ofmeans including by a tie member or, alternatively, by a pulling rod. Theslide member typically includes two fingers rests which extend from saidslide member and through two opposing slots in the wall of the housing.A user may therefore move the finger rests along the slots of thehousing to effect movement of the capture member. Movement of the fingerrests in a direction towards the proximal end of the housing typicallyeffects full withdrawal of the straightening member from the electrodearray.

The device of the present invention may further comprise a safetymechanism to prevent withdrawal of the straightening member before theelectrode array positioning member has moved to its second position andthe electrode array advanced into the cochlea of a subject. In thisregard, typically, the slide member has a spring member housed in arecess of said slide member. The spring member is preferably made from aresiliently flexible material and includes a main body which, on oneside is hingedly connected to a leg member. On an opposing side of themain body, the spring member includes a housing engagement portion whichextends from the main body and into a niche in the inner wall of thehousing of the device. When the housing engagement portion is positionedwithin the niche of the housing, any movement of the spring member andthe slide member relatively towards or away from the distal end of thehousing is prevented.

The slide member and the main body of the spring member may furtherinclude a groove which receives a portion of the electrode arraypositioning member thereby allowing the electrode array positioningmember to pass through the groove of the slide member as the electrodearray positioning member is moved from its first to its second position.

Typically, the electrode array positioning member comprises a number ofcomponents connected to or integral with one another. Preferably, theelectrode array positioning member includes a plunger member made up ofa thumb rest connected to or integral with a pushing arm. The thumb restand pushing arm are preferably made from a relatively hard material suchas a hard plastics material. The pushing arm may be connected to orintegral with an intermediate member which is typically made from arelatively more flexible material than the thumb rest and pushing arm.Further, the intermediate member can have a smaller cross-sectionaldiameter than the pushing arm. Finally, the intermediate member isconnected to or integral with an end member which receives the electrodearray. The end member is typically made from a suitably biocompatiblematerial such as surgical stainless steel or titanium.

Preferably, a portion of the pushing arm adjacent its connection withthe intermediate member is tapered to form a shoulder.

In use, the intermediate member typically passes along the groove of theslide and spring member when the plunger is actuated and the electrodearray is advanced into a cochlea. Movement of the intermediate memberalong the groove of the spring member does not disrupt the configurationof the resiliently flexible spring member. Accordingly, if the springmember is positioned such that the housing engagement member is withinthe niche in the housing, movement of the intermediate member of theelectrode array positioning member along the groove does not dislodgesaid housing engagement member and the spring member, slide member andthe capture member (which is connected to the slide member) aretherefore prevented from moving either in a direction relatively towardsor away from the distal end of the housing, that is, each of thesecomponents are fixed relative to the housing and the electrode arraypositioning member. This enables the electrode array positioning memberto be moved to its second position without the risk of the straighteningmember of the electrode array being withdrawn prematurely from saidarray.

As the electrode array positioning member reaches its second position,the tapered portion of the pushing arm extends into the groove in thespring member. The shoulder of the pushing arm pushes against a wall ofthe groove of the main body, causing the main body to move about itshinged joint with the leg member from a first position wherein the mainbody is relatively spaced from the leg member to a second positionwherein said main body is relatively less spaced from the leg member.The leg member is substantially prevented from moving relative to the_main body as it is relatively securely housed within a complementarystructure of the slide member. Movement of the main body of the springmember relative to the leg member disengages the housing engagementmember from the niche in the inner wall of the housing. With the housingengagement member disengaged from the inner wall of the housing, theslide member and the capture member are free to be moved by way of thefinger rests in a direction towards the proximal end of the housing.

In a preferred embodiment, the distal end of the housing abuts with thecochlea during the entire procedure of insertion of the electrode arrayand removal of the straightening member from the electrode array. Such adevice provides a stable tool for the insertion of the electrode arraywith less risk of slippage or accidental movement of the device duringinsertion of said array.

In another embodiment, the device may include a safety mechanism toprevent the distal end of the housing advancing too far into a cochleaof a subject. For example the device may include a cochleostomy stopperat or adjacent the distal, end which abuts with an edge of acochleostomy.

Other safety mechanisms include means to prevent the electrode arrayadvancing too far into a cochlea of a subject. In this regard, thedevice may include at least one stopper member which prevents theelectrode array positioning member from moving beyond a predeterminedposition. In one embodiment, the stopper member may include anengagement member which—engages with a latch member when the electrodearray positioning member is in its second position. Such engagement withsaid latch member prevents the electrode array positioning member movingany further beyond the second position. The latch member may bepositioned on any part of the device including on a wall of the housingor may form part of the capture member.

In another embodiment wherein the electrode array positioning member ismoved by movement of a slider along a slotted length of the housing, thelimiting factor in this case may be the length of a slot in the housingalong which the slider may travel.

Preferably, when the electrode array is loaded onto the device of thepresent invention, a portion of the electrode array extends a distanceof approximately 7 to 10 mm from the distal end of the housing. In thisembodiment, when the distal end of the housing is brought into abutmentwith a cochleostomy during a procedure, the leading tip of the electrodearray is positioned in the middle of the lumen near the back of thebasal turn of the scala tympani such that said leading tip of theelectrode does not exert pressure on the surrounding tissue.

As the electrode array is moved to its second position by movement ofthe electrode array positioning member, the electrode array continues tofollow a trajectory along the middle of the lumen of the scala tympanithereby avoiding pressure on the lateral wall of the cochlea thusminimising the potential for trauma to the lateral wall and the modiolarwall.

The device of the present invention may further include a means torelease an electrode array loaded thereon. In this embodiment, theelectrode array may be released by a surgeon should manual insertion bepreferred.

In another embodiment, the device of the present invention includes asafety clip member to prevent premature movement of the electrode arraypositioning member and thus movement of the electrode array. In thisregard, it is envisaged that a surgeon would be required to release thesafety clip prior to a surgical procedure.

It is envisaged that the safety clip may be positioned in engagementwith the electrode array positioning member at or adjacent its firstend. The safety clip may further abut with a portion of the housing suchthat the electrode array positioning member is prevented from moving toits second position.

Preferably, the safety clip is included in the packaging of the deviceto provide support during shipment and transportation. As a result, onceunpacked, the device is in the correct position for an assembledcartridge and electrode array to be attached.

The housing of the device may be made from a plastics material such aspolytetrafluoroethylene (PTFE) or polypropylene. Alternatively, thehousing may be made from a metal such as surgical steel, or acombination of metal and/or plastic. The choice of material may dependupon whether the device is manufactured as a re-usable or a disposabledevice.

Typically, the housing is tapered towards the distal end. Further, it ispreferred that the housing is angled in structure such as to provide agood line of vision for a surgeon during insertion of the electrodearray. In this embodiment, the electrode array positioning member andthe capture member may also be angled along their length to correspondwith the angled structure of the housing. Preferably, the angle of thehousing is in the region of 20 to 30°.

Typically, the housing includes a handle and a tip member wherein thetip member is angled relative to the handle. As noted above, the tipmember may be removably connected to the handle. Further, the tip membermay be rotated relative to the handle such that rotational orientationof an electrode array loaded on the device may be set by a surgeon asdesired or preferred for each surgery.

Preferably, a region of the housing adjacent the distal end includes awindow to allow a user to view the electrode array during loading of theelectrode array onto the device.

In a preferred embodiment, if the electrode array is loaded correctly,the user should be able to view the engagement portion of thestraightening member of the electrode array which is captured by thecapture member through the window.

The electrode array may be mounted on the device during the manufactureof the device. Typically, however, the electrode array is mounted on thedevice by a surgeon, immediately prior to surgery.

In a fourth aspect, the present invention consists in a device forinserting an electrode array into a cochlea of a subject and removing astraightening member of the electrode array, the device including ahousing extending from a proximal end to a distal end, said distal endadapted to receive a portion of the electrode array, the device furtherincluding an electrode array positioning member which is adapted tosubstantially extend through said housing from a first end to a secondend, said second end adapted to engage part of the electrode. array suchthat movement of the electrode array positioning member from a firstposition to a second position effects movement of the electrode arrayfrom a first position substantially within the housing to a secondposition substantially extending from the distal end of the housing; thedevice further including a capture member which extends at leastpartially through the housing and which has a region adapted to engage aportion of the straightening member of the electrode array and preventsaid straightening member from moving with the electrode array from saidfirst position substantially within the housing to said second positionsubstantially extending from the distal end of the housing.

In a fifth aspect, the present invention provides a method of insertingan electrode array into a cochlea of a subject using the device of thefirst aspect, said method including the steps of:

(a) positioning the device with the electrode array loaded thereon intoa surgical site of a subject until the distal end of the housing abutswith a cochleostomy in the wall of the cochlea;

(b) causing the electrode array positioning member to move from itsfirst position to its second position such that the electrode array iscaused to move from its first position substantially within the housingto its second position substantially extending from the distal end ofthe housing such that the electrode array is advanced into the cochleaof a subject; wherein the straightening member of the electrode array isengaged and held by the capture member of the device such that saidstraightening member does not advance into the cochlea with theelectrode array; and

(c) withdrawing the device of the invention from the subject.

In a sixth aspect, the present invention consists in a cartridge memberfor an electrode array, said electrode array having a straighteningmember, the cartridge member including an elongate body extending from afirst end to a second end, said elongate body having an internal lumenextending therethrough which is adapted to receive the electrode array;the cartridge member further including a window in a portion of thesidewall of the elongate body adjacent the first end wherein said windowenables a user to view a portion of the electrode array.

The electrode array may be loaded onto the cartridge member of the sixthaspect by feeding a portion of the straightening member of the electrodearray which extends from said electrode array into the second end of thecartridge member.

The elongate body further includes a slot along at least a portion ofits length to accommodate the leads of the electrode array. Preferably,the slot is substantially straight and constant in width as it extendsalong said at least a portion of the elongate body.

The electrode array is preferably oriented such that the electricalleads of the electrode array are substantially aligned with said slot ofthe cartridge member. The electrode array may then be guided into thecartridge member by pulling lightly on the electrical leads of theelectrode array until the portion of the straightening member whichextends from the electrode array also extends from the first end of thecartridge member.

The cartridge member and electrode array may be used with the devicedisclosed in the first aspect of the invention wherein the cartridgemember may be loaded onto the distal end of the housing of the deviceand the electrode array positioning member of the device caused toengage the electrode array within the cartridge member. The cartridgemay come pre-loaded with the electrode array or, alternatively, asurgeon may load the electrode array onto the cartridge prior to aprocedure.

In a preferred embodiment, a portion of the housing adjacent the distalend of the housing of the device includes a window. In this embodiment,as the cartridge member is loaded onto the device of the first aspect,the window of the cartridge member is aligned with the window in thehousing of the device.

Typically, if the engagement portion of the straightening member can beseen through the window of the housing, the cartridge member andelectrode array may be taken to be correctly mounted and a user may thencommence with the surgical procedure.

In a preferred embodiment, the cartridge may be made from a number ofmaterials and is preferably made from an electrically insulatingmaterial. Preferably, if not made of such a material, the cartridgeincludes an electrically insulating layer between the elongate body ofthe cartridge member and the electrode array. In this embodiment, ametal cartridge member may be coated on an inner wall defining the lumenof the main body with, for example, Paralyne, PTFE, a lubricioussilicone, or a plastic paint such as ABS.

In a seventh aspect, the present invention provides an electrode arrayfor insertion into a cochlea of a subject, the electrode array includingan elongate body which extends from a proximal end to a distal end and astraightening member extending along at least part of the length of theelongate body wherein at least a portion of the straightening memberextends beyond the proximal end of the elongate body, said at least aportion including a substantially spherical member, a substantiallyhemispherical member or an arrow-shaped member.

In an eighth aspect, the present invention is a method of implanting apre-curved electrode array into a cochlea of a subject, said pre-curvedelectrode array being maintained in a substantially straightconfiguration by a straightening member, said method including the stepsof

advancing the pre-curved electrode array into the cochlea; and

progressively removing the straightening member from the electrode arrayduring insertion such that the electrode array assumes an advancementpath that conforms to the natural shape of the cochlea thereby reducingthe incidence of damage to the sensitive structures of the cochlea.

It will be appreciated by persons skilled in the art that numerousvariations and modifications may be made to the invention as shown inthe specific embodiments without departing from the spirit or scope ofthe invention as broadly described. The present embodiments are,therefore, to be considered in all respects as illustrative and notrestrictive.

What is claimed is:
 1. An electrode insertion tool comprising: a handle having a proximal end, a distal end and a slot extending from the proximal end to the distal end; an orientation tube having an elongate body that extends from the distal end of the handle, the orientation tube having a lumen that receives an electrode stylet and a slot that aligns with a corresponding electrode in a predisposed orientation; a slide member that extends through the slot in the handle and moves from a proximal position to a distal position to advance an electrode from a distal end of the insertion tool; and a locking mechanism disposed within the orientation tube that engages the head of an electrode stylet and retains the stylet within the insertion tool as the electrode is advanced, wherein the orientation tube defines a window disposed adjacent the locking mechanism, wherein engagement between the head of a stylet and the locking mechanism is visible through the window.
 2. The electrode insertion tool of claim 1 wherein the locking mechanism comprises a generally cylindrical collar with at least one flap that resiliently deforms in a radial direction to engage the head of a stylet inserted from the distal end of the insertion tool.
 3. The electrode insertion tool of claim 2, further comprising a positioning member disposed generally co-axial with the cylindrical collar of the locking mechanism and coupled to the slide member such that movement of the slide member from the proximal position to the distal position moves the positioning member over the locking mechanism and advances an electrode from a distal end of the orientation tube.
 4. The electrode insertion tool of claim 1, further comprising a positioning member coupled to the slide member and passing over to the locking mechanism as the slide member is moved from the proximal position to the distal position.
 5. The electrode insertion tool of claim 1 wherein the slot extends fully from the proximal end to the distal end.
 6. A device for implanting an electrode array into the body of a subject, the device comprising: a housing having a proximal end and a distal end, wherein the distal end is configured to receive at least a portion of the electrode array; a capture member positioned at least partially within the housing, wherein the capture member is configured to receive an enlarged portion of a straightening member disposed within the electrode array, so as to hold the straightening member relative to the capture member once the enlarged portion is received by the capture member; and a slide member disposed within the housing and slidable from a proximal position to a distal position to advance an electrode from the distal end of the housing, wherein the housing defines a window, and wherein at least a portion of the capture member and the enlarged portion of the straightening member are arranged to be visible through the window.
 7. The device of claim 6, wherein the capture member comprises a resilient member configured to capture a tapered portion of the enlarged portion.
 8. The device of claim 6, wherein the capture member comprises a substantially cylindrical shape.
 9. The device of claim 6, wherein the slide member comprises a finger rest configured to be actuated by a user of the device.
 10. An electrode insertion tool comprising: a handle having a proximal end, a distal end and a slot extending from the proximal end to the distal end; an orientation tube having an elongate body that extends from the distal end of the handle, the orientation tube having a lumen that receives an electrode stylet and a slot that aligns with a corresponding electrode in a predisposed orientation; a slide member that extends through the slot in the handle and moves from a proximal position to a distal position to advance an electrode from a distal end of the insertion tool; and a locking mechanism disposed within the orientation tube that engages the head of an electrode stylet and retains the stylet within the insertion tool as the electrode is advanced, wherein the locking mechanism comprises a generally cylindrical collar with at least one flap that resiliently deforms in a radial direction to engage the head of a stylet inserted from the distal end of the insertion tool.
 11. The electrode insertion tool of claim 10, further comprising a positioning member disposed generally co-axial with the cylindrical collar of the locking mechanism and coupled to the slide member such that movement of the slide member from the proximal position to the distal position moves the positioning member over the locking mechanism and advances an electrode from a distal end of the orientation tube.
 12. The electrode insertion tool of claim 10, further comprising a positioning member coupled to the slide member and passing over to the locking mechanism as the slide member is moved from the proximal position to the distal position.
 13. The electrode insertion tool of claim 10 wherein the slot extends fully from the proximal end to the distal end. 